Disposable absorbent articles such as diapers and adult incontinence products are well known in the prior art. Such disposable absorbent articles collect and retain urine and fecal material deposited thereon by the wearer.
To date, most attempts in the prior art to treat the urine and fecal material collected and retained on the disposable absorbent article have been directed to handling urine insults. Dealing with fecal material collected by the disposable absorbent article is simply more difficult than dealing with urine insults, due to the complex rheology of low-viscosity fecal material.
Exemplary of the urine handling prior art are several attempts to provide disposable absorbent articles having a first topsheet which faces towards and contacts the body of the wearer, and a layer under the first topsheet, hereinafter referred to as a "secondary topsheet" which either absorbs urine, or transfers the urine to an underlying core for storage until the disposable absorbent article is removed from the wearer.
Typically, the first topsheet and secondary topsheet have different material properties. The secondary topsheet may have a smaller pore size than the first topsheet to assist in transfer of the urine through the topsheet. The first topsheet may be hydrophobic and more resilient when wetted than the secondary topsheet, in order to pass fluids through the topsheet to the secondary topsheet.
In yet another attempt in the prior art, the disposable absorbent article has a first topsheet, secondary topsheet and core. The secondary topsheet consists essentially of meltblown hydrophilic fibers and has a pore size greater than the pore size of the core. This arrangement allegedly allows the secondary topsheet to rapidly receive multiple liquid insults and distribute the liquid in the X-Y plane prior to absorption by the core. In yet another attempt vertical wicking capability for urine has been attempted, by using inflated cellulose fibers which are free of a surface finish or are crosslinked to one another.
In another attempt in the prior art, an absorbent core suitable for acquiring and containing liquids such as urine in a particularly effective and efficient manner comprises multiple layers. The first layer, which is closest to the wearer, comprises hydrophilic fibrous material and has an acquisition zone of a relatively lower average density than other portions of this layer, in order to quickly acquire discharged liquids. Below the first layer is a liquid handling layer comprising a resilient, low density high void volume material that is moisture insensitive in order to rapidly acquire liquid insults into itself through the acquisition zone and distribute these liquids throughout the liquid handling layer to a storage layer. The storage layer comprises a combination of fibrous material and discrete particles of absorbent gelling material, and allows the liquid handling layer to be drained of the liquids it has acquired, so that the liquid handling layer may have sufficient capacity to acquire and distribute subsequent loadings of liquids.
Of course, absorbent gelling materials are also now well known in the prior art. Absorbent gelling materials are polymeric materials capable of absorbing large quantities of fluids such as urine and retaining such absorbed fluids under moderate pressure. The effectiveness of the absorbent gelling materials is quite dependent upon the form, position and weight percentage of absorbent gelling materials which are incorporated into the core of the disposable absorbent article.
Attempts to optimize the use of absorbent gelling materials to aid in the acquisition and retention of urine include disposing a fluid storage lower layer of an absorbent core underneath an upper larger fluid acquisition/distribution layer. The storage layer has about 75 percent of the absorbent gelling material found in the disposable absorbent article. The fluid acquisition/distribution layer contains little or no absorbent gelling material. The fluid acquisition/distribution layer has a particular density which is preferably less than that of the lower fluid storage layer. About 55 percent of the absorbent gelling material is found in the front half of the disposable absorbent article, and additionally about 75 percent of the absorbent gelling material in the lower layer is found in the front two-thirds of the disposable absorbent article.
Yet other attempts in the prior art distribute the absorbent gelling material particles in a continuous, non-step-wise positive concentration gradient. This gradient may be found throughout either the entire core or may be present only in at least a portion of the thickness of the core. In various embodiments, the absorbent gelling materials of such an attempt in the prior art may be generally centered in the absorbent core, or alternatively, may be disposed along the upper and lower surfaces of the core. In yet another attempt in the prior art, the absorbent gelling materials are allegedly dispersed among the pores wherein at least 50 percent of the absorbent gelling materials have a size greater than the median pore size of the core when it is wet.
Examples of such attempts in the prior art to handle urine include U.S. Pat. Nos. 4,047,531 issued Sep. 13, 1977 to Karami; commonly assigned 4,673,402 issued Jun. 16, 1987 to Weisman et al.; 4,699,823 issued Oct. 13, 1987 to Kellenberger et al.; 4,798,603 issued Jan. 17, 1989 to Meyer et al.; 5,037,409 issued Aug. 6, 1991 to Chen et al.; 5,124,197 issued Jun. 23, 1992 to Bernardin et al.; commonly assigned 5,134,007 issued Jul. 28, 1992 to Reising et al.; and 5,147,343 issued Sep. 15, 1992 to Kellenberger.
However, all of these attempts to handle urine do little, if anything, to improve handling of low-viscosity fecal material which may also be present in the disposable absorbent article. Attempts to deal with fecal material include providing a first topsheet which conforms closely to the wearer and has an aperture. The aperture is hopefully registered with the anal opening, so that fecal material passes therethrough and into a void space. The first topsheet may comprise various elastic panels in order to conform closely to the skin of the wearer, and/or may have linear elastic strands. Improvements have been made in this area of the prior art, such as optimizing the material properties of the first topsheet. Such optimization makes the first topsheet more comfortable to the wearer and allows a single disposable absorbent article to fit a larger range of sizes of wearers.
Yet other attempts have been made in the prior art to provide an absorbent core with a hole therein, in order to receive the fecal material. The hole may be oblate shaped, so that it is longer and narrower than the aperture in the first topsheet, or may be diamond shaped. The hole in the core may be positioned below an aperture which has elastic strips around its edge.
Improvements to this genre of prior art disposable absorbent articles also include the addition of spacers. Spacers may be interposed between the first topsheet and the core, in order to ensure a void space is present to receive the fecal material.
Yet other attempts have been made in the prior art to provide barriers which limit the movement of fecal material to particular portions of the disposable absorbent article. The barriers limit the contact of the fecal material to a lesser portion of the skin of the wearer, than a comparable disposable absorbent article which has no barriers.
Still other attempts in the prior art provide barrier leg cuffs which are upstanding from the plane of the topsheet. The barrier leg cuffs prevent fecal material from breaching the perimeter of the disposable absorbent article.
Examples of such attempts in the prior art to handle fecal material include commonly assigned U.S. Pat. No. 4,892,536 issued Jan. 9, 1990 to DesMarais et al.; U.S. Pat. No. 4,909,803 issued Mar. 20, 1990 to Aziz et al.; U.S. Pat. No. 4,968,312 issued Nov. 6, 1990 to Khan; commonly assigned U.S. Pat. No. 4,990,147 issued Feb. 5, 1991 to Freeland; commonly assigned U.S. Pat. No. 5,037,416 issued Aug. 6, 1991 to Allen et al.; U.S. Pat. No. 5,062,840 issued Nov. 5, 1991 to Holt et al.; commonly assigned U.S. Pat. No. 5,171,236 issued Dec. 15, 1992 to Dreier et al.; and European Patent Application 0,355,740 A2 published Feb. 28, 1990 to Enloe.
However, none of these attempts in the prior art to handle fecal material solve the problem of low-viscosity fecal material which is prevalent in younger children, particularly those who are breast fed. Low-viscosity fecal material easily migrates within the disposable absorbent article under the influences of gravity and motion or pressure by the wearer.
The migration of the fecal material often moves it towards the perimeter of the disposable absorbent article, increasing the likelihood of leakage. The migration of the fecal material also smears it against the skin of the wearer, making cleanup more difficult. In order to clean the wearer, the caretaker must wipe the entire area of the skin which has encountered the fecal material and typically has to deal with a relatively large soiled area.
Accordingly, it is an object of this invention to provide a disposable absorbent article which overcomes the disadvantages present in the prior art. Particularly, it is an object of this invention to provide a disposable absorbent article which reduces leakage of fecal material from the disposable absorbent article and minimizes the amount of low-viscosity fecal material remaining on the skin of the wearer once the disposable absorbent article is removed. It is further an object of this invention to provide a disposable absorbent article which separates the fecal material into components.